Blanking method and apparatus



Jan. 3, 1967 J. G. F. HOTTE ETAL 3,295,354

BLANKING METHOD AND APPARATUS Filed April 16, 1964 5 Sheets-Sheet 1 2DIE OPENING Q 1967 J. G. F. HOTTE ETAL 3,295,354

BLANKING METHOD AND APPARATUS Filed April 16, 1964 5 Sheets-Sheet 2 1967J. a. F. HOTTE ETAL 3,295,354

BLANKING METHOD AND APPARATUS Filed April 16, 1964 5 Sheets-Sheet 5United States Patent Ofifice Patented Jan. 3, 1967 3,295,354 BLANKINGMETHOD AND APPARATUS Joseph G. F. Hotte, Lasaile, and Joseph L. R. A.Thomas,

Montreal, Quebec, Canada, assignors to Northern Electric Company,Limited, Montreal, Quebec, Canada Filed Apr. 16, 1964, Ser. No. 369,2987 Claims. (Cl. 72--468) This invention relates to a method and apparatusfor producing stampings from sheet material, and has particularreference to an apparatus for blanking such stampings from metallicsheet.

While many types of machine for punching sheet mate rial have beendesigned and used in the past in which the sheet material is placedbetween cooperating male and female cutting portions, the-re is alwaysthe problem of aligning the two separate parts of the die so that theyengage accurately and so that there is not excessive wear of one on theother. This is rendered particularly difficult when the part to beblanked is of unsymmetrical contour and the clearances between the maleand female parts are diflicult to measure. There is also the necessityof machining both of the die parts, which becomes increasingly expensiveas the contour becomes more complex.

It is an object of the invention to overcome these difficulties of theprior art by providing an apparatus in which machining of only one partof the die is required, in which very accurate alignment of the parts ofthe die can be secured and which by its particular structure producesvery cleanly blanked stampings.

More-particularly in accordance with the invention there is providedapparatus for blanking stampings from sheet material which comprises, apunch having a shaving portion contoured to an outline of the stampingto be blanked, a blanking portion on said punch being of decreasedcontour with respect to the said shaving portion, means for moving saidpunch in an operative path, adjustable cutter means surrounding the pathof travel of said punch, and conforming to the contour of said shavingportion, a die plate between said punch and said cutter means, saidpunch being brought down to punch out and shave an aperture in said dieplate to the contour of said shaving portion by co-operation with saidcutter means, said die plate subsequently forming a female portion of apunching apparatus for said sheet material, comprising said die plateand said punch blanking portion.

In accordance with the invention there is also provided the method ofblanking a stamping from sheet material which comprises the steps of,shaping a punch to the contour of said stamping to be blanked to form ashaving portion, further shaping said punch before said shaving portionto a contour smaller than that of the shaving portion to form a blankingportion, mounting said punch for movement in an operative path,adjusting cutter means to conform to the contour of said shaving portionsurrounding the path of travel of said punch, mounting a die plate onsaid cutter means, blanking and shaving said die plate by passing saidpunch blanking and shaving portions successively into said die plate,and placing sheet material to be punched on said die plate and passingsaid blanking portion into said sheet.

A description of the invention will now be made with reference to theaccompanying drawings in which,

FIGURE 1 shows a plan view of a die punch bed with adjustable cuttingblades,

FIGURE 2 shows a side view of the apparatus of FIGURE 1 including themale punch member and the blanked die plate,

FIGURE 3 is a partial side view of the apparatus when punching a dieplate and,

FIGURE 4 is a partial side view of the apparatus when blanking from asheet.

Having reference first to FIGURE 1 there is shown a female adjustabledie comprising a bed block 1, shaped to receive strip cutters 2 (seealso FIGURE 2) arranged with their broad dimensions vertically. Each setof cutters 2 is supported against its respective face 3 of block 1 underlateral pressure from a securing bolt 4. Each cutter 2 is forconvenience chamfered at one end and straight cut at the other. Cutters2 of various thickness are provided (see for instance cutters 6 and 7).The die block 1 is rigidly mounted on the working table 10 of ahydraulic or mechanical punch press by securing bolts 11. The pressincludes an overhead vertically reciprocating ram 13 to which is affixeda male punch 14 by a securing bolt 15.

The apparatus is first set up by accurately machining the punch member14 so that it includes a shaving portion 17 of the exact contour anddimension of the stamping to be blanked. Below the shaving part 17 is ablanking portion 18 which is of smaller periphery to allow a suitableclearance 42 between the blanking and shaving sur' faces (as describedlater). With the blades 2 in retracted position, well clear of the lineof travel of the punch 14, the punch is brought down into the squareaperture 20 in the center of the block 1 so that the leading end 21 ofits shaving portion is below the upper level of the blades 2. The blades2 are then all brought up so that they touch the shaving portion, and asclose an approximation as possible to the contour of the portion 17 isobtained by arranging for the chamfers or straight cut ends to followthe direction of the periphery of the shaving portion where itcooperates with that blade. In some instances wider blades will becalled for, in others narrower. Thus, for example, a fair approximationto the contour of the shaving portion can be obtained by the use of thethree blades 25, 24, and 27 in the position shown, whereas the straightcut ends would be more suitablein the area where blades 28, 29 and 3%contact their portions of the periphery of 17. When the adjustment ofthe blades has been made they are bolted up tightly in block 11 by therotation of bolts 4 (such as by Allen keys). Operation of the punch 14should now be possible so that the shaving portion 17 of the punchpasses into the aperture defined by the blades 2 but is not cut by them.

A die plate 36 of an appropriate thickness is placed on top of the bed 1and blades 2 (see FIGURE 2). The die plate is made of a material whoseductility generally embraces the range of that of tool steel, tokirksite. ()ther metals will suggest themselves to those skilled in theart but as will be seen later a tough substance which retains a welldefined aperture is required even though it need not have a very longlife as a die plate. The die plate 36 is clamped by bolts 49. The punch14 is brought down, it cooperates with the cutters 2, and the die plateis blanked out by the portion 18 and finally shaved by the portion 17.

The action which takes place can be seen in more detail in FIGURE 3. Asthe blanking portion 18 contacts the die plate 36, a roll-off edge 45 isformed in the plate, then the slug being forced out of the plate breaksaway at 46. The diameter is subsequently shaved at 47 to conform to thecontour of the shaving portion 17 of the ram. The slug 48 hascorresponding surfaces 49 formed during the roll-off and 44 at thebreak. Break 44 starts at the periphery of portion 18 and extends to theinner edges of blades 2.

Sheet material can now be blanked out accurately to produce stampings byrestricting the downward movement of punch 14 and allowing the blankingportion 18 of the punch 14 and the die plate 36 to cooperate as the twohalves of the cutting apparatus. The cutters 2 now form a support forthe die plate and prevent distortion through bending. By havingreference to FIGURE 4 the effect of the blanking portion 18 on the sheetmaterial 50 from which the stamping 51 is to be made can be seen. Thematerial 50 produces a roll-off portion 52, a corresponding roll 53being formed on the leading side of stamping 51. A break then occurs at54 diagonally and extends at its outermost periphery to follow the outercontour of the shaving portion 18. The edge quality of the stamping 51is comparable to that generally accepted in the art for stampingsproduced on standard blanking machines. It can be seen in FIGURE 4 thatthere is some distortion of the inner periphery of the walls of the holefrom which the stamping has been punched out of sheet 50. The clearance42 between portion 18 and shaving portion 17 is chosen, by trial ifnecessary, so that a clean blank is made in the sheet material by theblanking portion 18 and plate 36. Since the sheet may tend to cling tothe blanking portion 18, a suitable stripper 43 (see FIGURE 2) isprovided so that when the punch is raised the sheet material is forcedoff it.

When the production run has been completed or when the die plate 36shows wear, it may be discarded and a second die plate simply formed inthe same manner as the first.

This apparatus has the great advantages that only the punch 14 need beaccurately machined and retained for further use, and that the block 1with its associated blades 2 can be adapted to many shapes of punch.

We claim:

1. Apparatus for blanking stampings from sheet material which comprises,

a punch having a shaving portion contoured to an outline of a stampingto be blanked,

a blanking portion on said punch being of smaller size with respect tosaid shaving portion, and defining a clearance between the blanking andshaving portion,

means for moving said punch in an operative path,

adjustable cutter means surrounding the path of travel of said punch andconforming to the contour of said shaving portion, and

a die plate between said punch and said cutter means, said punch beingbrought down to punch out and shave an aperture in said die plate to thecontour of said shaving portion by cooperation with said cutter means,said die plate subsequently forming a female portion of a punchingapparatus for said sheet material comprising said die plate and saidpunch blanking portion.

2. Apparatus as defined in claim 1 wherein said cutter means comprises aplurality of longitudinally extending cutters movable in a directiontransverse to the axis of movement of said punch, and clamping means forfixing the position of said cutters.

3. Apparatus as defined in claim 2 comprising a block for mounting saidcutters, a relief in said block for receiving said cutters and screwmeans for fastening said cutters within said relief.

4. Apparatus as defined in claim 3 wherein said cutters are difierentlychamfered at opposite ends for conforming to the shape of said punch.

5. Ap aratus as defined in claim 2 comprising a stripper for removingsheet material adhering to said punch as said punch is returned from itsoperative path.

6. Apparatus as defined in claim 5 wherein said die plate is of materialselected from the group consisting of tool steel.

7. Apparatus as defined in claim 5, wherein said die "=late is ofkirksite.

References Cited by the Examiner UNITED STATES PATENTS 2,803,152 8/1957Wales 76-107 3,171,319 3/1965 Kyle 76107X GRANVILLE Y. CUSTER, JR.,Primary Examiner.

1. APPARATUS FOR BLANKING STAMPINGS FROM SHEET MATERIAL WHICH COMPRISES,A PUNCH HAVING A SHAVING PORTION CONTOURED TO AN OUTLINE OF A STAMPINGTO BE BLANKED, A BLANKING PORTION ON SAID PUNCH BEING OF SMALLER SIZEWITH RESPECT TO SAID SHAVING PORTION, AND DEFINING A CLEARANCE BETWEENTHE BLANKING AND SHAVING PORTION, MEANS FOR MOVING SAID PUNCH IN ANOPERATIVE PATH, ADJUSTABLE CUTTER MEANS SURROUNDING THE PATH OF TRAVELOF SAID PUNCH AND CONFORMING TO THE CONTOUR OF SAID SHAVING PORTION, ANDA DIE PLATE BETWEEN SAID PUNCH AND SAID CUTTER MEANS, SAID PUNCH BEINGBROUGHT DOWN TO PUNCH OUT AND SHAVE AN APERTURE IN SAID DIE PLATE TO THECONTOUR OF SAID SHAVING PORTION BY COOPERATION WITH SAID CUTTER MEANS,SAID DIE PLATE SUBSEQUENTLY FORMING A FEMALE PORTION OF A PUNCHINGAPPARATUS FOR SAID SHEET MATERIAL COMPRISING SAID DIE PLATE AND SAIDPUNCH BLANKING PORTION.